期刊
JOURNAL OF NEUROSCIENCE
卷 24, 期 2, 页码 495-499出版社
SOC NEUROSCIENCE
DOI: 10.1523/JNEUROSCI.4516-03.2004
关键词
testosterone; spine synapse density; CA1; hippocampus; unbiased stereological calculation; dihydrotestosterone
资金
- NIMH NIH HHS [R01 MH060858, MH60858] Funding Source: Medline
- NINDS NIH HHS [R01 NS042644, NS42644] Funding Source: Medline
The effects of androgen on the density of spine synapses on pyramidal neurons in the CA1 area of the hippocampus were studied in ovariectomized (OVX) adult female rats. Treatment of OVX rats with testosterone propionate (TP; 500 mug/d, s.c., 2 d) significantly increased spine synapse density (from 0.661 +/- 0.016 spine synapse/mum(3) in OVX rats to 1.081 +/- 0.018 spine synapse/mum(3) after TP treatment). A smaller, but still statistically significant, increase in synapse density (0.955 +/- 0.029 spine synapse/mum(3)) was observed in OVX animals after treatment with the nonaromatizable androgen dihydrotestosterone (DHT; 500 mug/d, s.c., 2 d). Administration of 1 mg of letrozole, a powerful nonsteroidal aromatase inhibitor, 1 hr before the steroid injections almost completely blocked the synaptic response to testosterone, resulting in a mean synapse density (0.723 +/- 0.003 spine synapse/mum(3)) only slightly higher than in OVX control rats. By contrast, the response to DHT was unaffected by letrozole pretreatment. These data suggest that androgen secretion during the female reproductive cycle may contribute to cyclical changes in hippocampal synaptic density. They also indicate that androgen treatment may be as effective as estrogen replacement in reversing the decline in hippocampal CA1 spine synapses that follows loss of ovarian function. Induction of hippocampal synapse formation by androgen is not mediated entirely via intracerebral estrogen biosynthesis, however, because aromatase-independent mechanisms also significantly affect CA1 spine synapse density.
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